Pytest-cov is extremely slow with xdist too

[emjeyforta]

Please go over all the sections and search
https://pytest-cov.readthedocs.io/en/latest/ or
https://coverage.readthedocs.io/en/latest/
before opening the issue.

Summary

When I run our tests with pytest-xdist, our entire tests about 1035 of them gets done in less than 35min
However, when we use pytest-cov it takes upto 1hr:15min which is tremondous.

I understand this is also due to the fact that the code instrumentation process of tracking the code takes some amount of time but this feels pretty exorbitant.

I also tried to install the python3-dev package but this does not seem to help as well

RUN apt-get update && \
    apt-get install -y python3-dev build-essential && \
    rm -rf /var/lib/apt/lists/*

With the above command, I see that it has made CTRACER available as well.

# python -c "import coverage; print(coverage.tracer.CTracer.__doc__)"
CTracer objects

We run our tests within the docker container.

Expected vs actual result

Pytest-cov should be able to complete the tests in and around the time when run without it

[KristianOellegaard]

I'm experiencing the same thing after moving our tests to run inside a docker container. I suspect Docker might be the problem.